In the past, as described in Japanese Unexamined Patent Application Publication No. H6-149051, a method of correcting image formation conditions in consideration of characteristic data of toner stored in advance in an IC chip disposed in a toner cartridge is known.
In order to improve the color reproducibility of a color image, an image forming apparatus forms a specific solid image on a photoconductive member and reads the toner concentration thereof by use of a sensor. When the toner concentration is low or the toner concentration is high, the non-uniformity of amounts of attached color toner is adjusted by adjusting development contrast to be the proper toner concentration. Since the amounts of attached color toner can be obtained uniformly by adjusting the development contrast, it is possible to stabilize the color reproducibility of the color image in comparison with the non-adjustment of the development contrast.
However, in the configuration described in the above-mentioned patent publication, the variation in physical property pf the toner due to environments is not considered and thus it cannot be said that the image formation condition is properly corrected.
When the amounts of attached toner become uniform but the toner cartridge is replaced with a toner cartridge filled with toner different color tones, the amounts of attached toner can be made to be uniform, but the color reproducibility of a color image varies from that before replacing the toner.
Accordingly, the invention provides an image forming apparatus that can properly make image control depending on a toner cartridge.